According to the National Blood Clot Alliance, once every six minutes, someone dies from a blood clot and blood clots lead as the number one killer of new mothers during and after childbirth.

According to Massachusetts General Hospital, a pulmonary embolism or PE is a blood clot that develops in the blood vessels elsewhere in the body and travels to an artery of the lung. A PE is a blood clot once it has lodged itself in the lung and formed a blockage of the artery.

While there are numerous risk factors for developing a PE, the most common include:

“Pregnancy puts a woman at increased risk of pulmonary embolism, so careful evaluation of pregnant patient is vital when they present with symptoms of chest pain and shortness of breath,” says Dr. Ravi Mohan, a radiologist and nuclear medicine specialist with the Joint Department of Medical Imaging for the University Health Network.

Left untreated mortality rates from pulmonary embolisms can be as high as 25 per cent. However, with the proper therapy, the rate of mortality decreases by nearly two-thirds to between two and eight per cent

One way to detect a potential clot in the body is known as a VQ or ventilation/perfusion scan. As Dr. Mohan points out, “nuclear medicine works from the inside out.”

In the case of a VQ scan two agents are given to the patient, one that looks at the airways (technegas) and the other to look at the blood vessels (Technetium 99m particles). As the agents, decay they give off gamma rays. These rays are in turn picked up by cameras, allowing physicians to detect abnormalities in the lungs.

These abnormalities are often seen as a decrease in the amount of perfusion or blood flow to a particular area in the patient while the ventilation or air flow will appear normal. It is this difference between the two parts of the tests that allows doctors to discover a blockage in the lung and thereby treat it.

Some of the symptoms may include.

It is important to point out that not all clots will present with symptoms in the patients regardless of size or location of the blood clot. “Patients may present with hypotension and shock in larger areas where as in patients with smaller blockages they have relatively few symptoms or no symptoms at all,” says Dr. Mohan

Treating pulmonary embolisms will vary from patient to patient but may include surgery, medications and oxygen therapy.

Starting in the 1950s, coal made up a large part of Ontario’s power mix. Coal was inexpensive, and Ontario lacked sufficient alternatives such as hydroelectric power or natural gas. By the late 1990s, however, links between adverse health effects and air pollution were firmly established, and much of this could be traced to Ontario’s coal-powered plants.

In 2003, Ontario began to replace its coal-fired plants with nuclear energy, completing the switchover in 2014. Over that time, air quality improved significantly, reducing respiratory illnesses and deaths.

ONTARIO’S EVOLVING POWER CHOICES

Ontario’s first electrical power supply came from a hydroelectric generating station on the Ottawa River in 1892. Hydro expanded rapidly across the province in the early 20th century. But it could not expand indefinitely: not every river can be dammed at places that are economically feasible and environmentally sensible. So, in the 1950s, Ontario added six coal-fired power stations to meet rising demand. Practical, large-scale nuclear power was not introduced in Ontario until the 1970s.

Coal remained an important part of this mix until the end of the 20th century, when it made up about a quarter of electricity generation in the province. By that time, the health risks of coal were becoming increasingly apparent.

THE LEGACY OF COAL

As burners of carbon-based fossil fuels, Ontario’s coal-fired power plants were heavy emitters of greenhouse gases, which threaten to accelerate climate change. They also emitted pollutants that affect human health directly: mercury, several air-borne carcinogens, and sulphur dioxide, which can make asthma symptoms worse. Sulphur dioxide can also react with other substances to create particulate matter – small solids or liquid drops in the air that can damage lungs.

Burning coal also releases nitrogen oxide, which contributes ground-level ozone, a principal factor in smog, which has a devastating effect on public health.

The province attributed 1,800 premature deaths and 1,400 cardiac and respiratory hospital admissions each year to smog. Several studies and reports had also highlighted the connection between Ontario’s air quality and public health.

In 2004, Toronto’s health department estimated that 1,700 Toronto residents died prematurely and 6,000 Torontonians were admitted to hospitals because of air pollution each year.

A 2005 report by the Ontario Ministry of Energy concluded that coal contributed to 928 hospital admissions and 1,100 emergency-room visits each year.

In 2005, a report by the Ontario Medical Association identified several other costs of air pollution, including at least $150 million in additional healthcare costs, $128 million in lost productivity, and a total of $2.4 billion in economic damage.

CHANGING THE MIX

Pressure was building to improve air quality. In 1999, the Ontario Public Health Association called on the province to replace its coal-fired power plants with cleaner power sources. The Ontario Medical Association had already declared an air pollution crisis.

Phasing coal out

In 2007, the Government of Ontario adopted the Integrated Power System Plan, guiding the province’s energy choices over 20 years. The plan aimed to stabilize prices, double renewable energy, and increase conservation. Its central goal was to replace toxic coal with cleaner power.

Ontario closed four coal-fired plants in 2010, and the last one in 2014 – making Ontario the first jurisdiction in North America to shut down coal-fired generation.

Phasing nuclear in

Even with the conservation measures set out in the plan, Ontario would have to supply electricity to make up for the closures of the coal-fired plants. Hydro was not an option, as Ontario had reached nearly 75% of its hydro capacity. Renewables such as wind and solar showed promise – and the plan aimed to double their use – but represented only tiny fraction of Ontario’s power supply, and could not be scaled up easily. Furthermore, solar and wind do not produce steady power around the clock, which is necessary to prevent brownouts.

The Government of Ontario recognizes nuclear power as a reliable and safe supplier of electricity. Since 2003, investment in Ontario’s power infrastructure has modernized three reactors (Pickering A Unit 1 and Bruce Units 3 and 4) and returned them to service. Nuclear power, which made up 37% of Ontario’s power mix in 2000, stood at 62% in 2014.

AIR POLLUTION: HOW ONTARIO’S POWER MIX STACKS UP

Any change in the power mix has environmental consequences – which leads Ontarians to ask whether the transition from coal to nuclear power might simply involve changing types of air pollution.

To answer this question, it is important to look at a power plant’s emissions from cradle to grave – including its construction, its fuel source, its waste products, and its eventual shutdown and decommissioning.

Smog factors

All methods of power generation emit particulate matter and contribute to ground-level ozone. However, nuclear energy emits far less particulate matter per unit of electricity than any fossil fuel – and less than wind.

Greenhouse gases

Greenhouse gas emissions by nuclear power are surprisingly low, considering the amount of construction needed to build a nuclear power plant. But those plants operate for decades, and emit no greenhouse gases while generating electricity.

And because of the vast amount of power that can be extracted from a small amount of uranium (20,000 times that of coal, by weight), emissions from nuclear power compare favourably with renewable energy sources, and are well ahead of fossil fuels.

CLEANER AIR, TODAY AND TOMORROW

Today, Ontarians enjoy cleaner air. According to the provincial government, “Ontario’s air quality has improved steadily since 1988. We have good air quality approximately 90 per cent of the time.” With the exception of a spike in 2012, which included a serious drought, the number and duration of smog advisories across the province has dropped steadily since 2003.

Cleaner air means better health. In Toronto, premature deaths attributed to air pollution dropped from 1,700 to 1,300 between 2004 and 2014, while hospitalizations fell from 6,000 to 3,550.

Even with this progress, there is still much room for improvement – especially as Ontario’s population ages and more people are at higher risk of health effects from air pollution. And, as the economy grows, Ontario will need a reliable, clean-air power source that keeps prices stable and affordable. Nuclear power can meet this need, partly because Canadian-designed reactors can be refuelled without shutting down, and because they draw from a fuel source that is abundant in Canada.

Recognizing this value, the province also put primary focus on nuclear energy in its 2013 Long-Term Energy Plan. It decided to upgrade and replace key components at the Bruce Power and Darlington sites, so they can continue to provide clean power for decades.